To determine which option results in the answer of 1, let's evaluate each response:
A. \( 50 + 90 = 140 \)
B. \( 3(80) = 240 \)
C. \( (-2.97)^0 = 1 \) (Any non-zero number raised to the power of 0 is 1)
D. \( 13 - (7.42)^0 = 13 - 1 = 12 \) (Since \( (7.42)^0 = 1 \))
The only option that results in the answer of 1 is:
C. \( (-2.97)^0 \)
So, the correct answer is C.